Global Specialties PB-503 - Manual - Manual (Page 12)

12
CHECKING OUT THE PB-503
The PB-503 may be checked out for proper operation by making a few simple
measurements and connections. Begin by connecting the AC line cord to a suitable
receptacle. The AC power indicator should light when the power switch is turned on.
Using a DC voltmeter, check for +5 volts between the ground terminal and the +5 volt
terminal. Repeat the measurement for the positive (+) variable supply terminal and the
negative (-) variable supply terminal. Check the variability of each supply by turning the
appropriate adjusting screw. To test the logic indicators, switch the +5/+V operating
voltage switch to the +5 position. The TTL/CMOS threshold switch can be in either
position. With no input to the logic indicators, all LEDs should be turned off. Connect
one end of a jumper wire to the + 5 volt terminal and the other end to logic indicator 1;
the red LED of logic indicator 1 should light. Repeat this test for logic indicators 2
through 8. Disconnect the jumper from the +5 volt terminal and connect it to the ground
terminal. Connect the other end to logic indicator 1; the green LED of logic indicator 1
should light. Repeat this test for logic indicators 2 through 8.
The function generator may be tested by connecting its output to one of the speaker
inputs. Connect the other speaker input to the ground terminal (or one of the connectors
on the ground bus strip). Switch the function generator range switch to "1" and the
Hz/kHz switch to "kHz". Move the frequency control all the way to the top. Move the
amplitude control upward until you hear a tone coming from the speaker. Switch the
waveform selector to select sine, square, and triangle. A changing but clearly audible
tone should be heard in each position. Changing the position of the frequency control
should vary the pitch of the tone.
If an oscilloscope is available, you may check the function generator for proper
waveform and frequency using standard measurement techniques.
The debounced pushbuttons can be checked by connecting one side of a resistor (20
Ω
to 100 K
Ω) to +5 volts and the other side to PB1-1, the NC point. Then connect PB1-1
to LED-1 with the Logic Indicator +5/+V switch in the +5 position, the red LED should
light when PB1 is pressed and the green LED should light when PB1 is released. Next,
move the connections from PB1-1 to PB1-2, the NO point. Now the red LED should be
lit when PB1 is not pressed, and the green LED should be lit when PB1 is pressed.
Repeat these steps to test PB2.
The logic switches can be tested by connecting the output of logic switches 1 through 8
to the input of logic indicators 1 through 8. Switch the logic switch +5V/+V high level
12 switch to +5, and switch the logic indicator +5/+V operating voltage switch to +5.
Select the CMOS position on the logic indicator TTL/CMOS threshold select switch.
Now the logic indicators should reflect the conditions of the logic switches, that is, red
LEDs will indicate switches in the high (logic "1") position and green LEDs will indicate
switches in the low (logic "0") position. Move each switch between its high and low
position to verify proper functioning. Switch the logic switch +5/+V high level switch to